Five-level power converter for bridge arm sharing type four-phase reluctance motor

Abstract

The invention provides a five-level power converter for a bridge arm sharing type four-phase reluctance motor, which comprises an energy storage capacitor module, an AC phase connecting part and a BD phase connecting part, and adopts the means that two non-adjacent phases share the same bridge arm and the adjacent phases use different capacitors to carry out normal-pressure excitation and normal-pressure demagnetization, so that independent work of each phase can be realized, and the reliability of the power converter is improved. And five level states of + 2, + 1, 0,-1 and-2 can be generated only by using the same number of devices as the asymmetric half-bridge power converter, so that normal-voltage excitation, zero-voltage follow current and normal-voltage demagnetization can be realized, rapid excitation and rapid demagnetization can also be realized, and the balance of neutral-point voltage of a series capacitor on a direct-current bus side can also be realized. The invention aims to provide more voltage choices for motor control by utilizing the multi-level equal-level advantage of the provided five-level power converter, so that the torque ripple of the motor is effectively reduced, and the operation efficiency and the dynamic response capability of the motor are improved.

Description

Technical Field

[0001] This invention belongs to the field of power converter technology for motors, specifically relating to a five-level power converter for a bridge-arm shared four-phase reluctance motor. Background Technology

[0002] Reluctance motors have coils wound only on the stator, offering advantages such as simple structure, low cost, high mechanical strength and reliability, low dependence on rare earth resources, wide speed range, and a certain degree of fault tolerance. They also feature high starting torque and low current, making them widely used in aviation, aerospace, home appliances, machinery, electronics, and other industries. Reluctance motors have applications in various fields. However, due to their unique doubly salient pole structure, they generate significant torque ripple during operation, which limits their further promotion and application. To effectively suppress torque ripple in reluctance motors, control algorithms can be improved, and the motor's structure and power conversion circuit can be optimized.

[0003] The power converter is a crucial component of a reluctance motor drive system, directly impacting its output performance. Currently, three-level power converters are widely used, with the asymmetrical half-bridge power converter being the most prevalent. Its circuit structure is as follows: Figure 14 As shown. Each phase output of the asymmetrical half-bridge power converter has only three voltage levels: 1, 0, and -1, as illustrated. Figure 15 As shown, when all switching transistors are turned on, the winding operates in excitation mode; as Figure 16 As shown, when only one switch is on, the winding operates in zero-voltage freewheeling mode; Figure 17 As shown, when all switching transistors are off, the winding operates in demagnetizing mode. The asymmetrical half-bridge power converter has a simple structure, good performance, and relatively diverse and simple control methods. However, the three-level power converter can only provide one excitation voltage and one demagnetizing voltage, failing to offer more voltage options for motor control. Furthermore, due to limitations in device capacity, it cannot meet the motor's requirements under different speeds and loads, resulting in limited torque ripple suppression and performance improvement for reluctance motors.

[0004] To address the problems of three-level power converters, researchers have proposed various five-level power converters with different structures. Chinese invention patent CN202210629353.2, entitled "Five-Level Power Converter for Switched Reluctance Motors Applied to Hybrid Vehicles," discloses a five-level power converter with the following circuit structure: Figure 18 As shown in the figure. This structure not only allows each phase to operate independently but also has a certain degree of fault tolerance. However, each phase requires four switching transistors and eight diodes, increasing the size, weight, and cost of the converter. The literature "A Method for Suppressing Torque Ripple in Switched Reluctance Motors Based on Five-Level Converters" proposes a circuit structure as shown in the figure. Figure 19 The diagram shows a five-level power converter. This structure reduces the number of components used while achieving independent commutation for each phase by having non-adjacent phases share the same bridge arm. This means that only 12 switches and 12 diodes are needed for four phases, but the structure requires four energy storage capacitors. Chinese invention patent CN202411181102.8, entitled "Five-Level Power Converter for Switched Reluctance Motors Achieving Rapid Excitation and Demagnetization," discloses such a converter. Figure 20 The circuit shown is a power conversion circuit for switched reluctance motors with any number of phases. While this structure enables independent operation of each phase and further reduces the number of components required, requiring only 3 switching transistors and 3 diodes per phase, it still requires multiple power supply modules or capacitors, resulting in a complex structure.

[0005] The document "Reduced Switch Multilevel Converter for Grid Fed SRM Drive toImprove Magnetization and Demagnetization Characteristics of an SRM" proposes the following: Figure 21 The five-level power converter shown, while significantly reducing the number of components through shared bridge arms, suffers from several drawbacks. When one phase operates in fast excitation mode (taking phase A as an example), switches S1, S2, and S6 are turned on, while diodes D1 and D6 are turned off. This prevents the other phases from operating in normal voltage excitation, normal voltage demagnetization, and fast demagnetization modes. Similarly, when one phase operates in normal voltage excitation mode, the other phases cannot operate in fast excitation, normal voltage demagnetization, and fast demagnetization modes. In summary, this structure exhibits phase-to-phase constraints when two or more phases overlap, preventing independent switching of the level state of each phase and severely limiting the further application of this power converter. Summary of the Invention

[0006] To address the issues of existing multi-level power converters, such as the large number of components and the inability to independently switch between adjacent phases, this invention employs a method where two non-adjacent phases share the same bridge arm and adjacent phases use different capacitors for constant voltage excitation and demagnetization. This not only enables independent operation of each phase but also generates five voltage levels (+2, +1, 0, -1, -2) using only the same number of components as an asymmetrical half-bridge power converter. This allows for constant voltage excitation, zero-voltage freewheeling, and constant voltage demagnetization, as well as rapid excitation and rapid demagnetization, and balances the midpoint voltage of the series capacitor on the DC bus side. This invention aims to leverage the multi-level advantages of the proposed five-level power converter to provide more voltage options for motor control, thereby effectively reducing motor torque ripple and improving motor operating efficiency and dynamic response.

[0007] The technical solution of this invention is as follows:

[0008] A five-level power converter for a bridge arm-shared four-phase reluctance motor includes an energy storage capacitor module, an AC phase connection section, and a BD phase connection section.

[0009] The energy storage capacitor module is composed of a first energy storage capacitor C1 and a second energy storage capacitor C2 connected in series;

[0010] The AC phase connection part consists of the AC phase left bridge arm, the AC phase right bridge arm, the AC phase common bridge arm, and the AC phase lateral diode. The AC phase left bridge arm and the AC phase right bridge arm each consist of a switch and a diode, the AC phase common bridge arm consists of a diode and two switches connected in series, and the AC phase lateral diode consists of a diode.

[0011] The BD phase connection part consists of the BD phase left bridge arm, the BD phase right bridge arm, the BD phase common bridge arm, and the BD phase lateral diode. The BD phase left bridge arm and the BD phase right bridge arm each consist of a switching transistor and a diode, the BD phase common bridge arm consists of a diode and two switching transistors connected in series, and the BD phase lateral diode consists of a diode.

[0012] The positive terminal of the energy storage capacitor module is connected to one end of all bridge arms, and the negative terminal of the energy storage capacitor module is connected to the other end of all bridge arms. The two ends of the A-phase winding are connected to the midpoint of the left bridge arm of the AC phase and the midpoint of the common bridge arm of the AC phase, respectively. The two ends of the C-phase winding are connected to the midpoint of the right bridge arm of the AC phase and the midpoint of the common bridge arm of the AC phase, respectively. The two ends of the B-phase winding are connected to the midpoint of the left bridge arm of the BD phase and the midpoint of the common bridge arm of the BD phase, respectively. The two ends of the D-phase winding are connected to the midpoint of the right bridge arm of the BD phase and the midpoint of the common bridge arm of the BD phase, respectively. The two ends of the AC-phase lateral diode are connected to the midpoint of the energy storage capacitor module and the midpoint of the series switch tube of the AC-phase common bridge arm, respectively. The two ends of the BD-phase lateral diode are connected to the midpoint of the energy storage capacitor module and the midpoint of the series switch tube of the BD-phase common bridge arm, respectively.

[0013] In a further preferred embodiment, the positive and negative terminals of the energy storage capacitor module refer to the connection points of the series-connected energy storage capacitors with the positive and negative terminals of the power supply, respectively; the left bridge arm of the AC phase includes a switching transistor S. AC1 and diode D AC2 The AC phase right bridge arm specifically includes the switching transistor S. AC4 and diode D AC4 The AC phase shared bridge arm includes a switching transistor S. AC2 S AC3 and diode D AC3 The AC phase lateral diode includes diode D. AC1 The left bridge arm of the BD phase includes a switching transistor S. BD1 and diode DBD2 The right bridge arm of the BD phase includes a switching transistor S. BD4 and diode D BD4 The BD phase shared bridge arm includes the switching transistor S. BD2 S BD3 and diode D BD3 The BD phase lateral diode specifically includes diode D. BD1 .

[0014] A further preferred embodiment is that in the left bridge arm of the AC phase, the switching transistor S... AC1 The collector of the diode is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the diode D. AC2 Cathode connection, diode D AC2 The anode is connected to the negative terminal of the energy storage capacitor module;

[0015] In the right bridge arm of the AC phase, the switching transistor S AC4 The collector of the diode is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the diode D. AC4 Cathode connection, diode D AC4 The anode is connected to the negative terminal of the energy storage capacitor module;

[0016] In the AC phase shared bridge arm, diode D AC3 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. AC2 Collector connection, switching transistor S AC2 Emitter and switch S AC3 Collector connection, switching transistor S AC3 The emitter is connected to the negative terminal of the energy storage capacitor module; in the AC phase lateral diode, diode D AC1 The cathode is connected to the midpoint of the energy storage capacitor module, and its anode is connected to the switching transistor S. AC3 Collector connection.

[0017] A further preferred embodiment is that, in the left bridge arm of the BD phase, diode D... BD2 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. BD1 Collector connection, switching transistor S BD1 The emitter is connected to the negative terminal of the energy storage capacitor module;

[0018] In the right bridge arm of phase BD, diode D BD4 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. BD4 Collector connection, switching transistor S BD4 The emitter is connected to the negative terminal of the energy storage capacitor module;

[0019] In the shared bridge arm of phase BD, the switching transistor S BD2 The collector is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the switch S. BD3Collector connection, switching transistor S BD3 Emitter and diode D BD3 Cathode connection, diode D BD3 The anode is connected to the negative terminal of the energy storage capacitor module; in the BD phase lateral diode, diode D BD1 The anode is connected to the midpoint of the energy storage capacitor module, and its cathode is connected to the switching transistor S. BD3 Collector connection.

[0020] In a further preferred embodiment, the midpoint of the energy storage capacitor module is the series connection point of the first energy storage capacitor C1 and the second energy storage capacitor C2.

[0021] A further preferred scheme is that the midpoint of the left bridge arm of the AC phase is the switching transistor S. AC1 The emitter and diode D AC2 The cathode connection point; the midpoint of the right bridge arm of the AC phase is the switching transistor S. AC4 The emitter and diode D AC4 The cathode connection point; the midpoint of the AC phase common bridge arm is diode D. AC3 anode and switching transistor S AC2 The collector connection point; the midpoint of the series switch transistors sharing the AC phase bridge arm is the switch transistor S. AC2 Emitter and switch S AC3 Collector connection point.

[0022] A further preferred embodiment is that the midpoint of the left bridge arm of phase BD is diode D. BD2 Anode and switching transistor S BD1 Collector connection point; the midpoint of the right bridge arm of phase BD is diode D. BD4 Anode and switching transistor S BD4 Collector connection point; the midpoint of the common bridge arm for phases BD is the switch S. BD3 Emitter and diode D BD3 Cathode connection point; the midpoint of the series switch transistors in the shared bridge arm of phases BD is switch transistor S. BD2 Emitter and switch S BD3 Collector connection point.

[0023] Beneficial effects

[0024] Compared with the prior art, the beneficial effects of this invention are:

[0025] To address the issues of existing multilevel power converters, such as the large number of components and the inability to independently switch adjacent phases, this invention employs a method where two non-adjacent phases share the same bridge arm and adjacent phases use different capacitors for constant voltage excitation and demagnetization. This solves the aforementioned problems, achieving fewer components, independent switching of each phase, and balanced voltage at the midpoint of the series capacitor on the DC bus side. This reduces the manufacturing cost, size, and weight of the power converter while also accelerating the excitation and demagnetization speed of the windings to some extent. It provides more voltage options for motor control, improves the motor's dynamic response, and helps suppress torque ripple and meet the motor's requirements under different speeds and loads.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0028] Figure 1 This is a circuit diagram of a five-level power converter for a four-phase reluctance motor proposed in this invention.

[0029] Figure 2 This is a schematic diagram of the AC phase connection of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0030] Figure 3 This is a schematic diagram of the BD phase connection of the five-level power converter for a four-phase reluctance motor proposed in this invention;

[0031] Figure 4 This is a schematic diagram of the A-phase fast excitation switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0032] Figure 5 This is a schematic diagram of the A-phase constant voltage excitation switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0033] Figure 6 This is a schematic diagram of the zero-voltage freewheeling switch state of the A-phase of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0034] Figure 7 This is a schematic diagram of the A-phase constant voltage demagnetizing switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0035] Figure 8 This is a schematic diagram of the A-phase fast demagnetizing switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0036] Figure 9 This is a schematic diagram of the B-phase fast excitation switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0037] Figure 10 This is a schematic diagram of the B-phase constant voltage excitation switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0038] Figure 11 This is a schematic diagram of the B-phase zero-voltage freewheeling switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0039] Figure 12 This is a schematic diagram of the B-phase constant voltage demagnetizing switch state of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0040] Figure 13 This is a schematic diagram of the five switching states of the B-phase rapid demagnetization of the five-level power converter for a four-phase reluctance motor proposed in this invention.

[0041] Figure 14 This is a schematic diagram of an existing asymmetric half-bridge power converter circuit.

[0042] Figure 15 A schematic diagram of the excitation state of a single-phase bridge arm in an existing asymmetric half-bridge power converter.

[0043] Figure 16 A schematic diagram of the zero-voltage freewheeling state of a single-phase bridge arm in an existing asymmetric half-bridge power converter.

[0044] Figure 17 A schematic diagram of the demagnetization state of a single-phase bridge arm in an existing asymmetric half-bridge power converter.

[0045] Figure 18 This is a circuit schematic diagram of a five-level power converter for a reluctance motor in the prior art;

[0046] Figure 19 This is a circuit schematic diagram of a five-level power converter for a reluctance motor in the prior art;

[0047] Figure 20 This is a circuit schematic diagram of a five-level power converter for a reluctance motor in the prior art;

[0048] Figure 21 This is a circuit schematic of a five-level power converter for a reluctance motor, based on existing technology. Detailed Implementation

[0049] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0050] like Figure 1 As shown, a five-level power converter for a four-phase reluctance motor with shared bridge arms includes an energy storage capacitor module, an AC phase connection section, and a BD phase connection section. The energy storage capacitor module is composed of a first energy storage capacitor C1 and a second energy storage capacitor C2 connected in series. The AC phase connection section consists of an AC phase left bridge arm, an AC phase right bridge arm, an AC phase shared bridge arm, and an AC phase lateral diode. The AC phase left bridge arm and the AC phase right bridge arm each consist of a switch and a diode, the AC phase shared bridge arm consists of a diode and two switches connected in series, and the AC phase lateral diode consists of a single diode. The BD phase connection section consists of a BD phase left bridge arm, a BD phase right bridge arm, a BD phase shared bridge arm, and a BD phase lateral diode. The BD phase left bridge arm and the BD phase right bridge arm each consist of a switch and a diode, the BD phase shared bridge arm consists of a diode and two switches connected in series, and the BD phase lateral diode consists of a single diode.

[0051] The positive terminal of the energy storage capacitor module is directly connected to one end of the bridge arm, and the negative terminal of the energy storage capacitor module is connected to the other end of the bridge arm; the two ends of the A-phase winding are connected to the midpoint of the left bridge arm of the AC phase and the midpoint of the common bridge arm of the AC phase, respectively; the two ends of the C-phase winding are connected to the midpoint of the right bridge arm of the AC phase and the midpoint of the common bridge arm of the AC phase, respectively; the two ends of the B-phase winding are connected to the midpoint of the left bridge arm of the BD phase and the midpoint of the common bridge arm of the BD phase, respectively; the two ends of the D-phase winding are connected to the midpoint of the right bridge arm of the BD phase and the midpoint of the common bridge arm of the BD phase, respectively; the two ends of the AC-phase lateral diode are connected to the midpoint of the energy storage capacitor module and the midpoint of the series switch tube of the common bridge arm of the AC phase, respectively; the two ends of the BD-phase lateral diode are connected to the midpoint of the energy storage capacitor module and the midpoint of the series switch tube of the common bridge arm of the BD phase, respectively.

[0052] The positive and negative terminals of the energy storage capacitor module refer to the connection points of the series-connected energy storage capacitors with the positive and negative terminals of the power supply, respectively; the left bridge arm of the AC phase specifically includes the switching transistor S. AC1 and diode D AC2 The AC phase right bridge arm specifically includes the switching transistor S. AC4 and diode D AC4 The AC phase shared bridge arm specifically includes the switching transistor S. AC2 S AC3 and diode D AC3 The AC phase lateral diode specifically includes diode D. AC1 The left bridge arm of the BD phase specifically includes the switching transistor S. BD1 and diode D BD2 The right bridge arm of the BD phase specifically includes the switching transistor S. BD4 and diode D BD4 The BD phase shared bridge arm specifically includes the switching transistor S. BD2 S BD3 and diode DBD3 The BD phase lateral diode specifically includes diode D. BD1 .

[0053] In the left bridge arm of the AC phase, the switching transistor S AC1 The collector of the diode is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the diode D. AC2 Cathode connection, diode D AC2 The anode is connected to the negative terminal of the energy storage capacitor module; in the right bridge arm of the AC phase, the switching transistor S... AC4 The collector of the diode is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the diode D. AC4 Cathode connection, diode D AC4 The anode is connected to the negative terminal of the energy storage capacitor module; in the AC phase shared bridge arm, diode D AC3 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. AC2 Collector connection, switching transistor S AC2 Emitter and switch S AC3 Collector connection, switching transistor S AC3 The emitter is connected to the negative terminal of the energy storage capacitor module; in the AC phase lateral diode, diode D AC1 The cathode is connected to the midpoint of the energy storage capacitor module, and its anode is connected to the switching transistor S. AC3 Collector connection.

[0054] In the left bridge arm of phase BD, diode D BD2 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. BD1 Collector connection, switching transistor S BD1 The emitter is connected to the negative terminal of the energy storage capacitor module; in the right bridge arm of the BD phase, diode D BD4 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. BD4 Collector connection, switching transistor S BD4 The emitter is connected to the negative terminal of the energy storage capacitor module; in the shared bridge arm of the BD phase, the switching transistor S... BD2 The collector is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the switch S. BD3 Collector connection, switching transistor S BD3 Emitter and diode D BD3 Cathode connection, diode D BD3 The anode is connected to the negative terminal of the energy storage capacitor module; in the BD phase lateral diode, diode D BD1 The anode is connected to the midpoint of the energy storage capacitor module, and its cathode is connected to the switching transistor S. BD3 Collector connection.

[0055] The specific point in the energy storage capacitor module is the series connection point of the first energy storage capacitor C1 and the second energy storage capacitor C2.

[0056] The midpoint of the left bridge arm of the AC phase is specifically the switching transistor S. AC1 The emitter and diode D AC2 The cathode connection point; the midpoint of the right bridge arm of the AC phase, specifically the switch S. AC4 The emitter and diode D AC4 The cathode connection point; the midpoint of the AC phase common bridge arm is specifically diode D. AC3 anode and switching transistor S AC2 The collector connection point; the midpoint of the series switch transistors sharing the AC phase bridge arm, specifically the switch transistor S. AC2 Emitter and switch S AC3 Collector connection point.

[0057] The midpoint of the left bridge arm of phase BD is specifically diode D. BD2 Anode and switching transistor S BD1 Collector connection point; the midpoint of the right bridge arm of phase BD, specifically diode D. BD4 Anode and switching transistor S BD4 Collector connection point; the midpoint of the common bridge arm for phases BD is specifically the switch S. BD3 Emitter and diode D BD3 Cathode connection point; the midpoint of the series switch transistors in the common bridge arm of phases BD is specifically switch transistor S. BD2 Emitter and switch S BD3 Collector connection point.

[0058] This bridge arm shared-type four-phase reluctance motor uses a five-level power converter, which can output U by controlling the combination of turning on and off of each switch in the AC phase connection section. dc、 U C1 , 0, -U C2 -U dc Five voltages; and by controlling the combination of turning on and off the various switches in the BD phase connection section, U can be output. dc、 U C2 , 0, -U C1 -U dc Five voltages.

[0059] Taking phase A as an example, when the switching transistor S... AC1 S AC2 and S AC3 When the circuit is turned on, the voltage across phase A winding is U. dc When the switching transistor S AC1 and S AC2 When the circuit is turned on, the voltage across phase A winding is U. C1 When the switching transistor S AC1 When the switch S is turned on, the A-phase winding is in zero-voltage freewheeling mode; when the switch S is turned on... AC2 When the circuit is turned on, the voltage across the A-phase winding is -U. C2When all switching transistors are off, the voltage across phase A winding is -U. dc .

[0060] Taking phase B as an example, when the switching transistor S... BD1 S BD2 and S BD3 When the circuit is turned on, the voltage across the B-phase winding is U. dc When the switching transistor S BD1 and S BD3 When the circuit is turned on, the voltage across the B-phase winding is U. C2 When the switching transistor S BD1 When the switch S is turned on, the B-phase winding is in zero-voltage freewheeling mode; when the switch S is turned on... BD3 When the circuit is turned on, the voltage across the B-phase winding is -U. C1 When all the switching transistors are off, the voltage across the B-phase winding is -U. dc .

[0061] The A-phase and C-phase windings of the four-phase reluctance motor are connected to the power converter in a similar manner, while the B-phase winding is connected to the power converter in a manner similar to the D-phase winding. Therefore, the output states of the remaining phases will be replicated below based on the analysis of phases A and B. Taking phases A and B of the four-phase reluctance motor as examples, the output states of the present invention will be described in further detail with reference to the accompanying drawings.

[0062] like Figures 4-8 As shown (dashed lines indicate current flow direction), the five different level switching states of phase A are as follows:

[0063] (1) Rapid excitation: such as Figure 4 As shown, when the switching transistor S AC1 S AC2 and S AC3 Conduction, diode D AC1 D AC2 and D AC3 When both are off, the current direction is from the positive terminal of the energy storage capacitor module through the switching transistor S. AC1 The current flows to phase A winding, and then sequentially from the winding through the switching transistor S. AC2 and S AC3 The current flows back to the negative terminal of the energy storage capacitor module. At this time, capacitors C1 and C2 discharge, applying a high voltage U to the windings. dc To achieve rapid excitation, the switching state is "+2".

[0064] (2) Atmospheric pressure excitation: such as Figure 5 As shown, when the switching transistor S AC1 S AC2 and diode D AC1 On, switch S AC3 and diode D AC2 and D AC3When cut off, the current flows from the positive terminal of the first energy storage capacitor C1 through the switching transistor S. AC1 The current flows to phase A winding, and then sequentially from phase A winding through switch S. AC2 and diode D AC1 The current flows back to the negative terminal of the first energy storage capacitor C1. At this time, capacitor C1 discharges, applying a low voltage U to the winding. C1 To achieve normal pressure excitation, the switching state is "+1".

[0065] (3) Zero-voltage follow current: such as Figure 6 As shown, when the switching transistor S AC1 and diode D AC3 On, switch S AC2 S AC3 and diode D AC1 and D AC2 When both are off, the current direction is from the switching transistor S. AC1 The current flows to phase A winding, and then from the winding through diode D. AC3 Flow back to switch S AC1 At this time, it is in zero-voltage freewheeling mode, and the switch status is "0".

[0066] (4) Demagnetization under normal pressure: such as Figure 7 As shown, when the switching transistor S AC2 and diode D AC1 D AC2 All are on, switch S AC1 S AC3 and diode D AC3 When both are cut off, the current flows from the negative terminal of the second energy storage capacitor C2 through diode D. AC2 The current flows to phase A winding, and then sequentially from the winding through the switching transistor S. AC2 and diode D AC1 The current flows to the positive terminal of the second energy storage capacitor C2. At this time, capacitor C2 is charging, and the voltage applied to the winding is -U. C2 This achieves demagnetization under normal pressure, with the switching state being "-1".

[0067] (5) Rapid demagnetization: such as Figure 8 As shown, when diode D AC2 D AC3 On, switch S AC1 S AC2 S AC3 and diode D AC1 When both are off, the current direction is from the negative terminal of the energy storage capacitor module through diode D. AC2 The current flows to phase A winding, and then from the winding through diode D. AC3 The current flows back to the positive terminal of the energy storage capacitor module. At this time, capacitors C1 and C2 are charged, and the voltage applied to the winding is -U. dc To achieve rapid demagnetization, the switch state is "-2".

[0068] like Figures 9-13 As shown (dashed lines indicate current flow direction), the five different level switching states of phase B are as follows:

[0069] (1) Rapid excitation: such as Figure 9 As shown, when the switching transistor S BD1 S BD2 and S BD3 Conduction, diode D BD1 D BD2 and D BD3 When both are off, the current direction is from the positive terminal of the energy storage capacitor module through the switching transistor S in sequence. BD2 and S BD3 The current flows to the B-phase winding, and then from the winding through the switching transistor S. BD1 The current flows back to the negative terminal of the energy storage capacitor module. At this time, capacitors C1 and C2 discharge, applying a high voltage U to the windings. dc To achieve rapid excitation, the switching state is "+2".

[0070] (2) Atmospheric pressure excitation: such as Figure 10 As shown, when the switching transistor S BD1 S BD3 and diode D BD1 On, switch S BD2 and diode D BD2 D BD3 When cut off, the current flows from the positive terminal of the second energy storage capacitor C2 through diode D in sequence. BD1 and switching transistor S BD3 The current flows to the B-phase winding, and then from the winding through the switching transistor S. BD1 The current flows back to the negative terminal of the second energy storage capacitor C2. At this time, capacitor C2 discharges, applying a low voltage U to the winding. C2 To achieve normal pressure excitation, the switching state is "+1".

[0071] (3) Zero-voltage follow current: such as Figure 11 As shown, when the switching transistor S BD1 and diode D BD3 On, switch S BD2 S BD3 and diode D BD1 D BD2 When both are off, the current flows from diode D. BD3 The current flows to the B-phase winding, and then from the winding through the switching transistor S. BD1 Return diode D BD3 At this time, it is in zero-voltage freewheeling mode, and the switch status is "0".

[0072] (4) Demagnetization under normal pressure: such as Figure 12 As shown, when the switching transistor S BD3 and diode DBD1 D BD2 All are on, switch S BD1 S BD2 and diode D BD3 When both are cut off, the current flows from the negative terminal of the first energy storage capacitor C1 through diode D in sequence. BD1 and switching transistor S BD3 The current flows to the B-phase winding, and then from the winding through diode D. BD2 The current flows to the positive terminal of the first energy storage capacitor C1. At this time, capacitor C1 is charging, and the voltage applied to the winding is -U. C2 To achieve demagnetization under normal pressure, the switching state is "-1".

[0073] (5) Rapid demagnetization: such as Figure 13 As shown, when diode D BD2 D BD3 On, switch S BD1 S BD2 S BD3 and diode D BD1 When both are off, the current direction is from the negative terminal of the energy storage capacitor module through diode D. BD3 The current flows to the B-phase winding, and then from the winding through diode D. BD2 The current flows back to the positive terminal of the energy storage capacitor module. At this time, capacitors C1 and C2 are charged by applying a -U voltage to the winding. dc To achieve rapid demagnetization, the switch state is "-2".

[0074] The five-level power converter proposed in this invention not only enables independent operation of each phase, but also outputs five different power levels using only eight switching transistors and eight diodes in four-phase operation. This reduces the manufacturing cost, size, and weight of the power converter. Furthermore, by using different charging and discharging capacitors in constant voltage excitation and demagnetization modes for adjacent phases, the midpoint voltage of the energy storage capacitor module is stabilized. Simultaneously, it accelerates the excitation and demagnetization speed of the windings to a certain extent, providing more voltage options for motor control, improving the motor's dynamic response capability, and helping to suppress torque ripple and meet the motor's requirements under different speeds and loads.

[0075] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A five-level power converter for a bridge-arm shared type four-phase reluctance motor, characterized in that: This includes the energy storage capacitor module, the AC phase connection section, and the BD phase connection section; The energy storage capacitor module is composed of a first energy storage capacitor C1 and a second energy storage capacitor C2 connected in series; The AC phase connection part consists of the AC phase left bridge arm, the AC phase right bridge arm, the AC phase common bridge arm, and the AC phase lateral diode. The AC phase left bridge arm and the AC phase right bridge arm each consist of a switch and a diode, the AC phase common bridge arm consists of a diode and two switches connected in series, and the AC phase lateral diode consists of a diode. The BD phase connection part consists of the BD phase left bridge arm, the BD phase right bridge arm, the BD phase common bridge arm, and the BD phase lateral diode. The BD phase left bridge arm and the BD phase right bridge arm each consist of a switching transistor and a diode, the BD phase common bridge arm consists of a diode and two switching transistors connected in series, and the BD phase lateral diode consists of a diode. The positive terminal of the energy storage capacitor module is connected to one end of all bridge arms, and the negative terminal of the energy storage capacitor module is connected to the other end of all bridge arms. The two ends of the A-phase winding are connected to the midpoint of the left bridge arm of the AC phase and the midpoint of the common bridge arm of the AC phase, respectively. The two ends of the C-phase winding are connected to the midpoint of the right bridge arm of the AC phase and the midpoint of the common bridge arm of the AC phase, respectively. The two ends of the B-phase winding are connected to the midpoint of the left bridge arm of the BD phase and the midpoint of the common bridge arm of the BD phase, respectively. The two ends of the D-phase winding are connected to the midpoint of the right bridge arm of the BD phase and the midpoint of the common bridge arm of the BD phase, respectively. The two ends of the AC-phase lateral diode are connected to the midpoint of the energy storage capacitor module and the midpoint of the series switch tube of the AC-phase common bridge arm, respectively. The two ends of the BD-phase lateral diode are connected to the midpoint of the energy storage capacitor module and the midpoint of the series switch tube of the BD-phase common bridge arm, respectively.

2. The five-level power converter for a bridge-arm shared four-phase reluctance motor according to claim 1, characterized in that: The positive and negative terminals of the energy storage capacitor module refer to the connection points of the series-connected energy storage capacitors with the positive and negative terminals of the power supply, respectively; the left bridge arm of the AC phase includes the switching transistor S. AC1 and diode D AC2 The AC phase right bridge arm specifically includes the switching transistor S. AC4 and diode D AC4 The AC phase shared bridge arm includes a switching transistor S. AC2 S AC3 and diode D AC3 The AC phase lateral diode includes diode D. AC1 The left bridge arm of the BD phase includes a switching transistor S. BD1 and diode D BD2 The right bridge arm of the BD phase includes a switching transistor S. BD4 and diode D BD4 The BD phase shared bridge arm includes the switching transistor S. BD2 S BD3 and diode D BD3 The BD phase lateral diode specifically includes diode D. BD1 .

3. The five-level power converter for a bridge-arm shared type four-phase reluctance motor according to claim 2, characterized in that: In the left bridge arm of the AC phase, the switching transistor S AC1 The collector of the diode is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the diode D. AC2 Cathode connection, diode D AC2 The anode is connected to the negative terminal of the energy storage capacitor module; In the right bridge arm of the AC phase, the switching transistor S AC4 The collector of the diode is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the diode D. AC4 Cathode connection, diode D AC4 The anode is connected to the negative terminal of the energy storage capacitor module; In the AC phase shared bridge arm, diode D AC3 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. AC2 Collector connection, switching transistor S AC2 Emitter and switch S AC3 Collector connection, switching transistor S AC3 The emitter is connected to the negative terminal of the energy storage capacitor module; in the AC phase lateral diode, diode D AC1 The cathode is connected to the midpoint of the energy storage capacitor module, and its anode is connected to the switching transistor S. AC3 Collector connection.

4. The five-level power converter for a bridge-arm shared four-phase reluctance motor according to claim 2, characterized in that: In the left bridge arm of phase BD, diode D BD2 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. BD1 Collector connection, switching transistor S BD1 The emitter is connected to the negative terminal of the energy storage capacitor module; In the right bridge arm of phase BD, diode D BD4 The cathode is connected to the positive terminal of the energy storage capacitor module, and its anode is connected to the switching transistor S. BD4 Collector connection, switching transistor S BD4 The emitter is connected to the negative terminal of the energy storage capacitor module; In the shared bridge arm of phase BD, the switching transistor S BD2 The collector is connected to the positive terminal of the energy storage capacitor module, and its emitter is connected to the switch S. BD3 Collector connection, switching transistor S BD3 Emitter and diode D BD3 Cathode connection, diode D BD3 The anode is connected to the negative terminal of the energy storage capacitor module; in the BD phase lateral diode, diode D BD1 The anode is connected to the midpoint of the energy storage capacitor module, and its cathode is connected to the switching transistor S. BD3 Collector connection.

5. The five-level power converter for a bridge-arm shared four-phase reluctance motor according to claim 1, characterized in that: The midpoint of the energy storage capacitor module is the series connection point of the first energy storage capacitor C1 and the second energy storage capacitor C2.

6. The five-level power converter for a bridge-arm shared type four-phase reluctance motor according to claim 3, characterized in that: The midpoint of the left bridge arm of phase AC is the switching transistor S. AC1 The emitter and diode D AC2 The cathode connection point; the midpoint of the right bridge arm of the AC phase is the switching transistor S. AC4 The emitter and diode D AC4 The cathode connection point; the midpoint of the AC phase common bridge arm is diode D. AC3 anode and switching transistor S AC2 The collector connection point; the midpoint of the series switch transistors sharing the AC phase bridge arm is the switch transistor S. AC2 Emitter and switch S AC3 Collector connection point.

7. A five-level power converter for a bridge-arm shared type four-phase reluctance motor according to claim 4, characterized in that: The midpoint of the left bridge arm of phase BD is diode D. BD2 Anode and switching transistor S BD1 Collector connection point; the midpoint of the right bridge arm of phase BD is diode D. BD4 Anode and switching transistor S BD4 Collector connection point; the midpoint of the common bridge arm for phases BD is the switch S. BD3 Emitter and diode D BD3 Cathode connection point; the midpoint of the series switch transistors in the shared bridge arm of phases BD is switch transistor S. BD2 Emitter and switch S BD3 Collector connection point.

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